. >> guest: was helpful as that the technology, take a smart phone or a tablet and you literally wavered over the code in the book and you get a video of the atkins case of many of the other cases we've covered. >> guest: one o of the cases recovered and fought with you can at the death penalty for juveniles. somebody who is under 18. this case involved a 17 year old who seem to be on a -- took an elderly woman out on a bridge, pushed her off. she drowned her and they pick him up at his high school the next day, and within hours he had a cheerful confession to police. and we describe is in the book but when you put the phone over the code, you can see the confession yourself. >> host: i thought the codes were neat way to just kind of come in almost takes the reader to even more into the book. and i was wondering what was the thought behind that? is this the direction in which books are going to be headed, especially nonfiction? it does create a great opportunity to just really grab your readers. >> guest: martin will explain this. i didn't understand what was. it just kind of gloomy away